The present invention relates to an arrangement for decoupling torsional vibrations in a gear transmission, especially in a control transmission between a crankshaft and a cam shaft of a reciprocating piston engine which consists of spur gears, in which a decoupling gear set meshing with the driving and driven gears is arranged between these two gears, and in which the decoupling gear set is composed of three coaxial gears arranged adjacent one another and mutually stressed by springs.
In gear transmissions which serve for the torque transmission, frequently torsional vibrations are introduced from the driving side or the driven side. These torsional vibrations lead to an alternate abutment at the tooth flanks. They cause clatter noises and at times also the breakage of teeth. Owing to gas- and mass-forces at the crank drive, such torsional vibrations occur particularly pronouncedly at crankshafts of reciprocating piston engines. If a control transmission consisting of spur gears is used between the crankshaft and the cam shaft, which is more advantageous for a precise control than a chain or belt drive, then these torsional vibrations are introduced into the control transmission. As at the same time torsional vibrations may also reach the control transmission from the cam shaft side, both torsional vibrations may overlap in one place within the control transmission in such an unfavorable manner that transmission shafts break. A decoupling arrangement for torsional vibrations is disclosed in the U.S. Pat. No. 2,966,806; it is referred to therein at times as "anti-backlash gear", a designation which is also utilized frequently in the German technical literature. A decoupling gear set is arranged between a driving gear and a driven gear which consists of three coaxial gears disposed one adjacent the other and mutually stressed by springs. The left split gear and the center gear mesh with the driving gear while the right split gear and the center gear mesh with the driven gear. The right split gear is stressed with respect to the center gear by one spring while the right split gear is stressed with respect to the center gear by a further spring. In case of a torsional vibration deflection at one of the split gears, the spring is stressed and returns the same into its relative starting position without conducting the torsional vibration through the decoupling arrangement.
It is therefore an object of the present invention to so improve a decoupling arrangement of the aforementioned type that it can be manufactured and assembled in a cost-favorable manner and is more effective in its function.
The underlying problems are solved according to the present invention in that drawsprings are arranged in apertures of the center gear disposed tangential to the latter which with their one spring ends are suspended at the left split gear and with the other spring ends at the right split gear. If the gears of the decoupling gear set are mutually stressed or spring-loaded by drawsprings, a torsional damping is achieved simultaneously with the torsional vibration decoupling because the end surfaces of the gear are placed against one another by the drawsprings. Such a gear set can be manufactured also cost-favorably and can be easily installed.